The design of passenger seats for aircraft requires consideration of passenger comfort, the number of seats and space limitations in a particular aircraft, and the location of the seat in the aircraft. Passenger seats generally include an aluminum base frame assembly to which are attached reclining seat backs, center arm rest assemblies, fold-down food table assemblies, and fully upholstered seat back and bottom cushion assemblies.
Economy or coach passenger seats are generally narrower and more densely spaced than business class or first class seats. Further, the seats of commuter aircraft are generally closer spaced and more dense than seats for larger wide-body international flights.
Business class and first class seats may be provided with a console with personal storage compartments, compartments for cocktail trays, and the like. A first class sleeper seat may include additional features such as a video monitor, an extendable leg rest, and other features for passenger comfort and convenience.
A wide-body aircraft may have center rows of, for example, five seats with aisles extending along each end of the center section of seats. Two, three, or more seats may be mounted between the aisle and the wall of the aircraft in each row of seats. Some rows of seats generally face the front of the aircraft while other rows face the rear of the aircraft. The number and spacing of seats adjacent emergency exits may differ from the seat spacing throughout the remainder of the aircraft.
The base frame for aircraft passenger seats is generally formed by a pair of stretcher tubes or rails which extend across the front and rear of the seat, spreader members supported by the stretcher tubes which extend along opposite sides of the seat for supporting the seat cushions and seat backs and leg assemblies spaced along the length of the stretcher tubes and connected to floor-mounted tracks for supporting the seats.
The spacing of spreaders and legs along the length of the stretcher tubes will vary for different types of seats and different seating arrangements. The position of legs on seats nearest the aisle and seats nearest the wall of the aircraft may vary depending upon the structural design of the aircraft, the number of seats in the row and the location of the row of seats in the aircraft. The connections between spreaders and stretcher tubes and between leg assemblies and stretcher tubes often vary depending upon the location of the spreaders on the stretcher tubes, the location of the legs on the stretcher tubes, whether the seat is a front facing seat or a rear facing seat.
Heretofore the construction and maintenance of aircraft seats has been very expensive because operations have been labor intensive. Further the size and shape of components of the seat vary depending upon the location of the installation in the aircraft, resulting in a multitude of parts that must be kept in inventory for proper maintenance. Periodic maintenance required on aircraft seats and minor changes in a seat, for example, the installation of a telephone in a seat back or arm rest, generally requires replacement or disassembly of the entire seat merely for replacing or installing a component in the seat assembly.
U.S. Pat. No. 5,224,755 discloses a passenger seat leg assembly with an energy absorbing zone. Straps extend around stretcher tubes and are bolted to the leg assemblies for supporting the seats.
U.S. Pat. No. 5,069,505 issued to Amthor et al. on Dec. 3, 1991 discloses a seat divider having hemi-shells at the forward and rearward ends that are oriented downward for engaging the front and rear transverse struts of an aircraft seat base frame. The connection between the seat divider and the tubular transverse struts is formed by an adjustable strap retainer. These strap retainers can be tightened by a clamping element to impart the necessary tension to the retainer strap to permit rotary motion about the transverse strut, but only by overcoming friction. The hemi-shell surface and strap retainer are designed to slide over the transverse strut with the strut passing therebetween, but this connection interferes with the connection between the rear leg and the rear tubular transverse strut, which is also formed by an adjustable strap retainer that slides over the transverse strut. Thus, the base frame must be disassembled to separate the horizontal tubular members from the legs in order to replace or change a spreader. Further, forces encountered during crash testing are concentrated in the clamp elements and retainer straps.
U.S. Pat. No. 4,229,040 issued to Howell et al. on Oct. 21, 1980 discloses a typical base frame for an aircraft seat. The seat support structure includes a pair of spaced horizontal tubular members that extend beneath individual seating stations. These tubular members are maintained in a predetermined spaced relationship by a multiplicity of spacing members each located adjacent to the individual seating stations. Spreaders, which are described as beam members, are equipped with a forward enlarged cylindrical portion to receive and encircle the forward horizontal tubular member and a second enlarged cylindrical portion to receive and circle the rear horizontal tubular member. Because the enlarged cylindrical portions are designed to slide over the horizontal tubular members with the tubular members passing therethrough, the cylindrical portions interfere with the legs attached to the horizontal tubular members that vertically support the tubular members. Thus, the base frame must be disassembled to separate the horizontal tubular members from the legs in order to replace or change a spreader.
U.S. Pat. No. 4,375,300 issued to Long et al. on Mar. 1, 1983 discloses a framing system for an aircraft passenger seat including support members mounted on stretcher tubes. The front end of the arm support on spreader is secured by a single vertically extending screw to the top of the stretcher tube. The rear of the spreader is secured by a horizontally extending bolt to the rear stretcher tube.
The important structural requirements for safety must be met and at the same time the airline operator needs to be able to easily and cost effectively maintain the seats. It is often necessary to change the seating configuration in the aircraft to meet different passenger and market needs. In the past, the assembly and disassembly of the seats has been a complicated, time consuming, and expensive process, often requiring that most of the seat support structure be disassembled in order to move or change the seating configuration. Furthermore, every reduction in the weight of the seats without reducing the structural integrity saves the airline fuel and reduces operating expenses.
Accordingly, it is an object of the present invention to provide an improved aircraft seat support structure in which the base frame spreaders for the passenger seats can be quickly and easily mounted or removed from the rest of the support structure without reducing the structural strength of the seat. It is another object of the invention to provide an improved aircraft seat support structure with a reduced number of parts. It is another object of the invention to provide an aircraft seat support structure that is capable of meeting the normal safety requirements while being lighter in weight.
It is another object of this invention to provide a design which will allow placement of spreaders and legs along a stretcher tube without regard to having a stretcher and a leg exist in the same vertical plane.